This copy is for your personal non-commercial use only. To order presentation-ready copies of Toronto Star content for distribution to colleagues, clients or customers, or inquire about permissions/licensing, please go to: www.TorontoStarReprints.com

As the Zika crisis grows, scientists are scrambling to understand how the virus spreads

The questions surrounding the Zika outbreak seem to grow every day, as emerging evidence suggesting the virus can be spread in several ways, not just by mosquito bites.

Mosquito nets protect pregnant women at a hospital in San Salvador, El Salvador, Friday. Even with mounting evidence of other modes of transmission, scientists still say the Aedes aegypti mosquito is likely the main culprit behind the spread of Zika. (JOSE CABEZAS / REUTERS)

As Zika’s impact continues to grow, health officials are still struggling to answer basic questions about how the virus works.

“I wish we knew more about Zika today. I wish we could do more about Zika today,” said Dr. Tom Frieden, director of the U.S. Centers for Disease Control and Prevention in a press conference Friday. “I understand that this is a stressful situation for women and families, and particularly for women who are pregnant.”

But scientists are learning more by the day, according to Frieden, and public health bodies are tweaking their recommendations as new pieces of the puzzle emerge.

Here is what we have recently learned — and what we still don’t know — about how Zika spreads.

Urine and saliva

Article Continued Below

On Friday, researchers with Brazil’s Fiocruz research institute announced they had found live Zika virus in saliva and urine samples taken from two patients. This adds to evidence from previous studies of a Zika outbreak in French Polynesia in 2013 and 2014 that also detected the virus in these bodily fluids.

The CDC said it has yet to see data from the Brazilian research, and more work is needed before recommendations can be made based on the findings.

But at least one Brazilian official is already warning pregnant women to avoid kissing people who are not their partners, or sharing cutlery, glasses and plates with people exhibiting symptoms.

“This is not a generalized public health measure, for the love of God,” said Paulo Gadelha, president of the Fiocruz research institute. He stressed both the seriousness of the discovery, and that it was too soon to say how it could impact the epidemic.

Friday’s announcement coincided with the start of Carnival, a five-day-long bacchanal that sees millions of people take part in alcohol-fueled parties where kissing as many people as possible is a top pastime. Gadelha underscored that the discovery didn’t need to alter Carnival plans for anyone but pregnant women.

To address the possibility of sexually transmitted Zika — which health officials say is likely rare — the CDC updated its recommendations on Friday. Men with pregnant partners who visit (or live in) Zika-affected areas should abstain from sex or use condoms for the duration of the pregnancy, the CDC said. As for men with partners who are not pregnant, they should “consider” abstinence or condom use if they visit or live in a Zika-affected country. As yet, there have been no reported cases of women infecting men through sex.

Blood transfusions

On Thursday, Brazilian authorities reported their first two cases of Zika transmission through blood transfusions. One involved a patient who received blood in May 2015 from a donor infected by Zika; genetic tests showed the patient was infected, though he never showed symptoms. The other involved a gunshot victim who was infected after multiple transfusions.

Blood banks around the world are asking donors to wait for several weeks after travelling to Zika-affected countries before giving blood. Canadian Blood Services says blood donors should wait for 21 days after visiting a country outside of Canada, the continental U.S. or Europe.

Mosquitoes

Despite emerging evidence the virus can be transmitted in other ways, public health officials continue to emphasize that mosquitoes — primarily the day-biting Aedes aegypti — remain the main culprit in spreading Zika.

“Everything that we’ve seen with not just Zika but dengue and chikungunya — spread by the same mosquito — suggests that this is the overwhelming cause and route of transmission,” Frieden said Friday. “But any time there are lots of cases of a condition, you will see rare or occasional phenomena happening sometimes, and we think that’s what’s happening here.”

The Toronto Star and thestar.com, each property of Toronto Star Newspapers Limited, One Yonge Street, 4th Floor, Toronto, ON, M5E 1E6. You can unsubscribe at any time. Please contact us or see our privacy policy for more information.

More from the Toronto Star & Partners

LOADING

Copyright owned or licensed by Toronto Star Newspapers Limited. All rights reserved. Republication or distribution of this content is expressly prohibited without the prior written consent of Toronto Star Newspapers Limited and/or its licensors. To order copies of Toronto Star articles, please go to: www.TorontoStarReprints.com